Sliding breech block mechanism

ABSTRACT

This invention comprises, in a gun, a sliding breech block mechanism wherein the breech block is connected to at least one pivot carried by a rocker member which incorporates a convex rocker segment in hypocyclic engagement with a coacting concave track formed in, or attached to, the gun: means being provided for inducing, on recoil of the gun, hypocyclic motion of each rocker segment relative to its track whereby the consequent movement of the pivot or pivots operates the breech block.

United States Patent Brant Aug. 29,\l972 [54] SLIDING BREECH BLOCK OTHERPUBLICATIONS MECHANISM Marks Mechanical Engineers Handbook, TheodoreInventor! p Trevor Brim, 4 The Baumeister, 6th Ed. McGraw-Hill, 1958,sec. 2, pp.

bms, Waltham Abbey, Essex, En- 0 1 gland 22 i May 19 PrimaryExaminer-Stephen C. Bentley [21] PP No'z 549,429 Attomey-Cushman, Darby& Cushrnan [57] ABSTRACT This invention eomprises, in a gun, a slidingbreech 58 Field of Sea l'c is 24 186 mechanism wherein breech is 1 4nected to at least one pivot carried by a rocker member whichincorporates a convex rocker segment [56] References Cited in hypocyclicengagement with a coacting concave track formed in, or attached to, thegun: means being UNITED STATES PATENTS provided for inducing, on recoilof the gun, hypocyclic 2,398,453 motion of each rocker segment relativeto its track 4/1946 Summerbill ..89/24 whereby the consequent movementof the pivot or pivots operates the breech block.

15 Claims, 10 Drawing Figures Patented Aug. 29, 1972 3,687,001

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10 Sheets-Sheet 9 Attorneys Patented Aug. 29, 1972 10 Sheets-Sheet 10 W$nv2ng r MM, 44%KM4 Attorneys SLIDING BREECH BLOCK MECHANISM Thisinvention relates to breech mechanisms and is particularly concernedwith a mechanism, actuated by the recoil of a weapon after firing, foroperating its sliding breech block.

Use is made of the motion of a circle rolling, internally, around thecircumference of a second, coplanar circle. Hereinafter, two circlescoacting in this way will be said to be in hypocyclic engagement, themotion of the rolling circle being referred to as hypocyclic motion;these terms being, of course equally applied to cylinders or gears, 01'segments thereof, which coact in this manner.

This invention comprises, in a gun, a sliding breech block mechanismwherein the breech block is connected to at least one pivot carried by arocker member which incorporates a convex rocker segment in hypocyclicengagement with a coacting concave track formed in, or attached to, thegun; means being provided for inducing, on recoil of the gun, hypocyclicmotion of each rocker segment relative to its track whereby theconsequent movement of the pivot or pivots operates the breech block.

By inserting suitable linkages between the breech block and rockermembers, a large variety of arrangements of the mechanism is possible.Clearly, however, the use of complicated linkages, particularly thosewhich involve changes in the direction of motion, can lead toconsiderable losses in efficiency. In order to avoid this, it ispreferred to use a special form of the hypocyclic motion device in whichthe radius of the track is twice that of the rolling member. In thiscase any point on the circumference of the rolling member will move backand forth along a diameter of the track, its specific diametral pathbeing predetermined by its position on the circumference.

In a preferred form of the invention therefore, substantially, theradius of each rocket segment is half that of its track, their mutuallyparallel axes being perpendicular to the line of action of the breechblock; and each pivot is so located on the pitch circle of a rockersegment that it moves, during hypocyclic motion of the segment, along adiametral path in the coacting track, parallel to the line of action ofthe breech block. The term pitch circle is used herein to defined theeffective, track engaging surface of a rocker segment, that is to say,the actual pitch circle of a gear or the circumference of a cylinder orthe circle of which a segment of either forms a part. Any convenientnumber of rocker members and tracks may be employed and a track mayaccommodate one or more rocker members.

The required hypocyclic motion may be conveniently induced by theengagement of one or more rocker members or of attachments thereto, asthe gun recoils, with one or more actuating members mounted on a fixedstructure such, for example, as a cradle in which the gun is mounted. Anactuating member may be a stop located in the path traversed by a rockermember as the gun recoils or, for example, a rack arranged to engage apinion or a toothed segment which operates the rocker member. In orderto allow for variations in recoil of the gun, the arrangement ispreferably such that operative engagement between the rocker member andthe actuating member is terminated when the breech block is fully openedso that further recoil can take place without further movement of thebreech block.

One form of the invention will now be more particularly described, byway of example only, with reference to the accompanying drawings inwhich:

FIGS. 1 to 3 are horizontal sections through the breech portion of agun,

FIG. 4 is a section on the line IV-IV of FIG. 1.

FIG. 5 is a side view in the direction V of FIG. 1 but with the stopmember and cradle omitted for clarity,

FIG. 6 is a detail of the stop member,

FIG. 7 is a horizontal section through the breech portion of a gun,showing an alternative arrangement,

FIG. 8 is a view in the direction VIII of FIG. 7,

FIG. 9 is a section on the line IX- IX of FIG. 7, and

FIG. 10 is a detail of an alternative stop member.

The gun I is provided, in normal manner, with a breech block 2 arrangedto slide horizontally in a breech recess 3 in a breech ring 4; thebreech block 2 having, on its upper and lower faces, projections 5 (FIG.9) which engage in grooves 6 in the upper and lower faces of the recess3 to retain the block therein.

Formed in the breech ring 4, forward of the breech recess 3 and on thatside of the gun I to which the breech block moves on opening, is asubstantially quadrantal, concave cylindrical track 7 whose axisintersects the path of the breech lock 2 and is perpendicular to boththe gun axis and the line of action of the breech block. Pivoted to thebreech block 2 is a rocker member 8 of generally semi-cylindrical formhaving a convex, curved surface comprising rather less than a halfcylinder, at each extremity of which, at opposite ends of its boundingdiameter, are formed radially projecting lugs 10a, 10b, the remaining,plane surface being parallel to the bounding diameter on the sidethereof remote from the curved surface. The curved surface constitutes arocker segment 9 in rolling contact with the track 7 and its radius ishalf that of the track. A pivot pin 11 is mounted in the lugs 10aadjacent the breech block 2 the pivot axis passing through theintersection of the circumference of the rocker segment 9 with itsbounding diameter, the axis of the pivot 1 1 being parallel to those ofthe track 7 and the rocker segment 9. The location of the pivot 11 inthe breech block 2 is such that its axis lies in that diametral plane ofthe track 7 which is perpendicular to the gun axis. With thisarrangement, if the rocker segment 9 is constrained to undergohypocyclic motion relative to the track 7, the pivot 11 and the lugs 10bat the other end of the bounding diameter of the rocker segment 9(hereinafter referred to as the contact lugs) will move respectivelyalong those diameters of the track 7 which are perpendicular to andparallel to the gun axis, the motion of the pivot 11 serving to open orclose the breech.

In order to produce the hypocyclic motion required to open the breech, astop member 12 is mounted on the gun cradle 13 in the path of movementwhich will be followed, on recoil of the gun 1, by the contact lugs 10b.This stop member 12 is, on recoil of the gun 1, engaged by the contactlugs 10b which are thus caused to move forward relative to the gun 1,parallel to its axis, the resulting hypocyclic motion of the rockermember 8 being used to open the breech against the action of breechblock return springs. A spring loaded catch 14 (shown in FIGS. 7 to 9only) moves into engagement with a notch 14a in the breech block 2, asits opens, to retain it in its open position until the catch 14 isreleased by the insertion of a new round 15 of ammunition into thebreech, whereupon the breech is closed by the action of the returnsprings and the rocker segment 9 returns to its initial position byhypocyclic motion in the reverse direction. The new round 15 may beinserted manually or automatically in known manner.

In a preferred form, the stop member 12 consists of a toggle devicemounted on the cradle 13 and extending forwardly, toward the gun I,along the line of move ment of the contact lugs b. On recoil, the lugsltlb engage the cross member 16 at the forward end of the toggle devicewhereby the rocker segment 9 is caused to undergo hypocyclic motion inits track 7 to open the breech. In its fully open position the breechblock 2 or, as shown, a projection 2a thereon is arranged to engage thetoggle hinge 17 to break the toggle lock whereafter the recoil cancontinue without further movement of the breech block 2. On run out, thetoggle device is returned to its locked position by a ferrule 18actuated by a spring 18a. The forward end of the toggle is constrainedto move parallel to the gun axis by the engagement of the pins 36 withgrooves 37 in the cradle 13. In the alternative form of toggle shown inFIG. 10 return to the locked position is achieved by the action of aspring 39 wound around the toggle pivot 17a the free ends of whichspring engage fore and aft cross members 38a, 38b of the toggle.

An alternative stop member may be in the form of a spring loaded buffer19 (FIG. 7) 7) whose spring 20 is sufficiently strong to achievecompression of the breech block return springs but which will becompressed to permit further recoil when the breech block 2 engages asolid stop at the fully open position. Various other forms of stopmember will occur to those versed in the art.

The breech block 2 is urged toward its closed position by a pair ofbreech block return springs. In the embodiment shown in FIGS. 7 to 9these springs 21 are in compression between the block 2 and a yoke 22which spans that end of the breech recess 3 towards which the breechblock 2 moves on opening. These springs 21 are coiled around guide rods23 fixed to the yoke 22 and in register with corresponding bores 24 inthe adjacent face of the breech lock 2, each of which bores 24 serves tohouse one end of the corresponding spring 21 and to receive the spring21 and guide rod 23 as the breech is opened. This version also employs apair of rocker segments instead of the single segment shown in theversion ofFIGS. l to 5.

In the preferred arrangement shown in FIGS. 1 to 6, however closure ofthe breech is efiected by one or more breech block return springs 28acting indirectly upon the breech block through the rocker member 8which is thereby caused to execute hypocyclic movement in the reversedirection to close the breech. The rocker member 8 is pivoted, throughthe contact lugs 10b, to a slide 25 which is movable, parallel to thegun axis, in a guideway 26 carried by the gun 1. The pivot 27, like thebreech block pivot 11 is located on the pitch circle of the rockersegment 9. The slide 25 is urged toward its rearward position by thebreech block return springs 28 which are helical springs in compressionbetween the forward end of the guideway 6 and the forward end of theslide 25, the said springs 28 being mounted around guide rods 29 fixedto the guideway 26 and extending into bores 30 in the slide 25. Thesesprings 28 act, on release of the breech retaining catch 14 by insertionof a new round 15 of ammunition, to return the slide 25 to its rearwardposition thereby inducing hypocyclic motion of the rocker member 8 inthe reverse direction to close the breech.

In order to avoid any possibility of premature opening of the breech dueto inertia of the moving parts during the initial high acceleration ofthe gun after firing, at which time the gas pressure in the gun maystill be fairly high, a spring latch 31 is pivoted to the rear end ofthe guideway 26 which latch is biased by spring 32 toward engagementwith a coacting notch 33 on the slide 25. This latch 31 preventsmovement of the slide 25 until it is disengaged therefrom by the actionof cam surfaces 34 upon the cradle 13, with which the upward extensions35 of the latch 31 come into engagement at a predetermined stage of thegun recoil.

Although it is convenient to arrange the axes of the rocker segment 8and track 7 perpendicular to the gun axis as well as to the line ofaction of the breech block 2, this former condition is not essential.The segment can be made to roll in a track whose axis is inclinedobliquely, or is even parallel, to the gun axis by wedge action producedby the engagement of suitably inclined faces on the rocker member 8 andstop member 12.

It will be clear that considerable variations of the above describedarrangements may be made within the scope of the invention.

I claim:

1. A breech mechanism for a gun equipped with a sliding breech block,which mechanism incorporates a rocker member; a convex rocker segmentincorporated in the rocker member; a pivot carried by the rocker memberto which pivot the breech block is connected; a concave track movablewith the gun and in hypocyclic engagement with the rocker segment andmeans for inducing, on recoil of the gun, hypocyclic motion of therocker segment relative to the track whereby the consequent movement ofthe pivot operates the breech block.

2. A mechanism as claimed in claim 1 wherein the radius of the track istwice that of the rocker segment and the pivot is located on the pitchcircle of the rocker segment whereby, during the hypocyclic motion ofthe segment, the pivot moves rectilinearly along a diameter of thetrack.

3. A mechanism as claimed in claim 2 wherein the axis of the trackintersects the line of action of the breech block and the pivot is solocated on the said pitch circle that it will move along that diameterof the track which is parallel to the said line of action.

4. A mechanism as claimed in claim 1 wherein the axes of the track androcker segment are perpendicular to the gun axis and to the line ofaction of the breech block.

5. A mechanism as claimed in claim 1 wherein the rocker segmentcomprises a part cylindrical surface on the rocker member, which surfaceis in rolling contact with the track which is also part cylindrical.

6. A mechanism as claimed in claim 1 having a fixed structure relativeto which the gun recoils, wherein the means for inducing the hypocyclicmotion of the rocker segment comprises an actuating member attached tothe fixed structure for engaging the rocker member during recoil of thegun, to open the breech.

7. A mechanism as claimed in claim 6 having means for rendering theactuating member inoperative after the breech block has reached thefully open position whereby further recoil can occur without furthermovement of the breech block.

8. A mechanism as claimed in claim 7 wherein the actuating membercomprises a toggle device consisting of two members hinged together anda spring for urging said members to a toggle locked position in whichthe two members are in line; the rear end of the device being pivoted tothe fixed structure, from which the device extends forwardly in the pathtraversed by the rocker member on recoil of the gun, the forward end ofthe toggle device being restrained from lateral movement by engagementin guide channels in the fixed member; said toggle device being engagedby the rocker member during recoil of the gun to open the breech andbeing so positioned that the breech block, in its fully open position,engages the hinge to break the toggle lock whereafter further recoil ofthe gun, accompanied by folding of the toggle device, can occur withoutfurther movement of the breech block.

9. A mechanism as claimed in claim 1 including a fixed structurerelative to which the gun recoils and at least one breech block returnspring opposing the opening motion of the breech block and wherein themeans for inducing the hypocyclic motion of the rocker segment comprisesa spring buffer mounted on the fixed structure in the path traversed bythe rocker member on recoil of the gun, the strength of the bufferspring being sufficient to overcome the resistance of the breech blockreturn springs to open the breech, said spring however being compressedafter the breech block has reached its limit of travel therebypermitting further recoil without further movement of the breech block.

10. A modification of the mechanism as claimed in claim 1 incorporatinga plurality of rocker segments.

11. A gun having a breech ring; a breech block slidably mounted in abreech recess in the breech ring; a pair of breech block return springsurging the breech block toward its closed position; a cradle in whichthe gun is mounted and relative to which it can recoil on firing; and asliding breech mechanism comprising a quadrantal concave cylindricaltrack formed in the breech ring forward of the breech recess and on thatside of the gun to which the breech block moves on opening, the axis ofsaid track being perpendicular to the gun axis and to the line of actionof the breech block and intersecting the latter; a substantiallysemicylindrical rocker member pivoted to the breech block, its curvedsurface, whose radius is half that of the track, constituting a rockersegment in hypocyclic engagement with the track; a radially extendinglug at each end of the bounding diameter of the segment to one of whichlugs the breech block is pivoted, the pivot axis intersecting thecircumference of the rocker segment and the line of action of the breechblock; and actuating member attached to the cradle in the path traversedby the second lug as the gun recoils to engage said lug to cause thesegment to roll forwardly executing hypocyclic motion relative to thetrack whereby the pivot axis is moved along the diameter of the track toopen the breech; a spring latch mounted on the breech ring for engagingthe breech block to maintain it open until released in ertion of a newrou d wher after the breech b d ck is closed by the action of the returnsprings.

12. A gun as claimed in claim 11 having yoke fixed across that end ofthe breech recess to which the breech block moves on opening; a pair ofguide rods extending from said yoke into aligned bores in the breechblock; the breech block return springs being located around the guiderods and in compression between the yoke and the breech block.

13. A gun as claimed in claim 11 including a guideway located in thebreech ring; a slide, slidable parallel to the gun axis, in saidguideway, the slide being pivoted to the second lug of the rockersegment; and a pair of guide rods parallel to the gun axis extendingrearward from the forward end of the guideway into aligned bores in theslide; the breech block return springs being located around said guiderods and in compression between the guideway and the slide whereby onrelease of the breech latch the breech block return springs act upon theslide and hence on the rocker segment which consequently executeshypocyclic motion in the reverse direction to close the breech.

14. A gun as claimed in claim 13 including a spring catch mounted on theguideway for engaging the slide to prevent premature opening of thebreech due to inertia of the mechanism, on recoil, before the gaspressure in the gun has sufficiently reduced; and a cam surface on thecradle arranged to engage and release said catch after the pressure hassufficiently reduced but before engagement of the rocker segment withthe actuating member.

15. A gun as claimed in claim 11 wherein the actuating member is atoggle device comprising a pair of members hinged together and a springurging the toggle to a locked position in which the two members are inline; said toggle device being pivoted at one end to the cradle andextending forwardly therefrom in the path traversed by the second lug ofthe rocker segment on recoil of the gun, the forward end of the toggledevice being restrained from lateral movement by engagement with guidechannels formed in the cradle; the toggle device being positioned so asto be engaged by the breech block at its fully open position to breakthe toggle lock whereafter further recoil can occur, accompanied byfolding of the toggle, without further movement of the breech block.

1. A breech mechanism for a gun equipped with a sliding breech block,which mechanism incorporates a rocker member; a convex rocker segmentincorporated in the rocker member; a pivot carried by the rocker memberto which pivot the breech block is connected; a concave track movablewith the gun and in hypocyclic engagement with the rocker segment andmeans for inducing, on recoil of the gun, hypocyclic motion of therocker segment relative to the track whereby the consequent movement ofthe pivot operates the breech block.
 2. A mechanism as claimed in claim1 wherein the radius of the track is twice that of the rocker segmentand the pivot is located on the pitch circle of the rocker segmentwhereby, during the hypocyclic motion of the segment, the pivot movesrectilinearly along a diameter of the track.
 3. A mechanism as claimedin claim 2 wherein the axis of the track intersects the line of actionof the breech block and the pivot is so located on the said pitch circlethat it will move along that diameter of the track which is parallel tothe said line of action.
 4. A mechanism as claimed in claim 1 whereinthe axes of the track and rocker segment are perpendicular to the gunaxis and to the line of action of the breech block.
 5. A mechanism asclaimed in claim 1 wherein the rocker segment comprises a partcylindrical surface on the rocker member, which surface is in rollingcontact with the track which is also part cylindrical.
 6. A mechanism asclaimed in claim 1 having a fixed structure relative to which the gunrecoils, wherein the means for inducing the hypocyclic motion of therocker segment comprises an actuating member attached to the fixedstructure for engaging the rocker member during recoil of the gun, toopen the breech.
 7. A mechanism as claimed in claim 6 having means forrendering the actuating member inoperative after the breech block hasreached the fully open position whereby further recoil can occur withoutfurther movement of the breech block.
 8. A mechanism as claimed in claim7 wherein the actuating member comprises a toggle device consisting oftwo members hinged together and a spring for urging said members to atoggle locked position in which the two members are in line; the rearend of the device being pivoted to the fixed structure, from which thedevice extends forwardly in the path traversed by the rocker member onrecoil of the gun, the forward end of the toggle device being restrainedfrom lateral movement by engagement in guide channels in the fixedmember; said toggle device being engaged by the rocker member duringrecoil of the gun to open the breech and being so positioned that thebreech block, in its fully open position, engages the hinge to break thetoggle lock whereafter further recoil of the gun, accompanied by foldingof the toggle device, can occur without further movement of the breechblock.
 9. A mechanism as claimed in claim 1 including a fixed structurerelative to which the gun recoils and at least one breech block returnspring opposing the opening motion of the breech block and wherein themeans for inducing the hypocyclic motion of the rocker segment comprisesa spring buffer mounted on the fixed structure in the path traversed bythe rocker member on recoil of the gun, the strength of the bufferspring being sufficient to overcome the resistance of the breech blockreturn springs to open the breech, said spring however being compressedafter the breech block has reached its limit of travel therebypermitting further recoil without further movement of the breech block.10. A modification of the mechanism as claimed in claim 1 incorporatinga plurality of rocker segments.
 11. A gun having a breech ring; a breechblock slidably mounted in a breech recess in the breech ring; a pair ofbreech block return springs urging the breech block toward its closedposition; a cradle in which the gun is mounted and relative to which itcan recoil on firing; and a sliding breech mechanism comprising aquadrantal concave cylindrical track formed in the breech ring forwardof the breech recess and on that side of the gun to which the breechblock moves on opening, the axis of said track being perpendicular tothe gun axis and to the line of action of the breech block andintersecting the latter; a substantially semi-cylindrical rocker memberpivoted to the breech block, its curved surface, whose radius is halfthat of the track, constituting a rocker segment in hypocyclicengagement with the track; a radially extending lug at each end of thebounding diameter of the segment to one of which lugs the breech blockis pivoted, the pivot axis intersecting the circumference of the rockersegment and the line of action of the breech block; and actuating memberattached to the cradle in the path traversed by the second lug as thegun recoils to engage said lug to cause the segment to roll forwardlyexecuting hypocyclic motion relative to the track whereby the pivot axisis moved along the diameter of the track to open the breech; a springlatch mounted on the breech ring for engaging the breech block tomaintain it open until released by insertion of a new round whereafterthe breech block is closed by the action of the return springs.
 12. Agun as claimed in claim 11 having a yoke fixed across that end of thebreech recess to which the breech block moves on opening; a pair ofguide rods extending from said yoke into aligned bores in the breechblock; the breech block return springs being located around the guiderods and in compression between the yoke and the breech block.
 13. A gunas claimed in claim 11 including a guideway located in the breech ring;a slide, slidable parallel to the gun axis, in said guideway, the slidebeing pivoted to the second lug of the rocker segment; and a pair ofguide rods parallel to the gun axis extending rearward from the forwardend of the guideway into aligned bores in the slide; the breech blockreturn springs being located around said guide rods and in compressionbetween the guideway and the slide whereby on release of the breechlatch the breech block return springs act upon the slide and hence onthe rocker segment which consequently executes hypocyclic motion in thereverse direction to close the breech.
 14. A gun as claimed in claim 13including a spring catch mounted on the guideway for engaging the slideto prevent premature opening of the breech due to inertia of themechanism, on recoil, before the gas pressure in the gun hassufficiently reduced; and a cam surface on the cradle arranged to engageand release said catch after the pressure has sufficiently reduced butbefore engagement of the rocker segment with the actuating member.
 15. Agun as claimed in claim 11 wherein the actuating member is a toggledevice comprising a pair of members hinged together and a spring urgingthe toggle to a locked position in which the two members are in line;said toggle device being pivoted at one end to the cradle and extendingforwardly therefrom in the path traversed by the second lug of therocker segment on recoil of the guN, the forward end of the toggledevice being restrained from lateral movement by engagement with guidechannels formed in the cradle; the toggle device being positioned so asto be engaged by the breech block at its fully open position to breakthe toggle lock whereafter further recoil can occur, accompanied byfolding of the toggle, without further movement of the breech block.